On Fri, Mar 28, 2014 at 2:52 PM, Fred Drake <f...@fdrake.net> wrote: > On Fri, Mar 28, 2014 at 5:19 PM, Greg Ewing <greg.ew...@canterbury.ac.nz> > wrote: > > ISO 8601 doesn't seem to define a representation for > > negative durations, though, so it wouldn't solve the > > original problem. > > Aside from the horribleness of the ISO 8601 notation for a duration, it's > best not to confuse the notions of duration and delta. Notionally, a delta > contains more information than a duration.
and less -- really it's different. A duration would be really useful actually, for things like "next month", etc,. IIRC, mxDateTime has something for this, but it's NOT the same as a timedelta. timedelta appears to be analogous to ISO 8601's " time interval", which requires 1. Start and end, such as "2007-03-01T13:00:00Z/2008-05-11T15:30:00Z" 2. Start and duration, such as "2007-03-01T13:00:00Z/P1Y2M10DT2H30M" 3. Duration and end, such as "P1Y2M10DT2H30M/2008-05-11T15:30:00Z" 4. Duration only, such as "P1Y2M10DT2H30M", with additional context information http://en.wikipedia.org/wiki/ISO_8601#Time_intervals I don't think there is or should be a any direct mapping from timedelta to ISO duration. -Chris -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception chris.bar...@noaa.gov
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